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Anterior cruciate ligament tear induces a sustained loss of muscle fiber force production.

ABSTRACT: INTRODUCTION:Patients with anterior cruciate ligament (ACL) tears have persistent quadriceps strength deficits that are thought to be due to altered neurophysiological function. Our goal was to determine the changes in muscle fiber contractility independent of the ability of motor neurons to activate fibers. METHODS:We obtained quadriceps biopsies of patients undergoing ACL reconstruction, and additional biopsies 1, 2, and 6 months after surgery. Muscles fiber contractility was assessed in vitro, along with whole muscle strength testing. RESULTS:Compared with controls, patients had a 30% reduction in normalized muscle fiber force at the time of surgery. One month later, the force deficit was 41%, and at 6 months the deficit was 23%. Whole muscle strength testing demonstrated similar trends. DISCUSSION:While neurophysiological dysfunction contributes to whole muscle weakness, there is also a reduction in the force generating capacity of individual muscle cells independent of alpha motor neuron activation. Muscle Nerve, 2018.

SUBMITTER: Gumucio JP

PROVIDER: S-EPMC6051936 | biostudies-other | 2018 Jan

REPOSITORIES: biostudies-other

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Anterior cruciate ligament tear induces a sustained loss of muscle fiber force production.

Gumucio Jonathan P JP Sugg Kristoffer B KB Enselman Elizabeth R Sibilsky ERS Konja Alexis C AC Eckhardt Logan R LR Bedi Asheesh A Mendias Christopher L CL

Muscle & nerve 20180118

<h4>Introduction</h4>Patients with anterior cruciate ligament (ACL) tears have persistent quadriceps strength deficits that are thought to be due to altered neurophysiological function. Our goal was to determine the changes in muscle fiber contractility independent of the ability of motor neurons to activate fibers.<h4>Methods</h4>We obtained quadriceps biopsies of patients undergoing ACL reconstruction, and additional biopsies 1, 2, and 6 months after surgery. Muscles fiber contractility was as ...[more]

PMID: 29346717

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Project description:BackgroundAnterior cruciate ligament (ACL) rupture is the most common ligament injury treated surgically by orthopaedic surgeons. The gold standard for the treatment of the majority of primary ACL tears is ACL reconstruction. However, novel methods of repair, such as bridge-enhanced ACL repair (BEAR), are currently being investigated as alternatives to reconstruction. To assess patients for midsubstance repair suitability, clarify the prognostic implications of injury location and damage, and evaluate the results of a repair technique, it is important to have a baseline classification system or grading scale that is reproducible across surgeons, particularly for multicenter collaboration. Currently, no such system or scale exists.PurposeTo develop an arthroscopic ACL tear classification system and to evaluate its interobserver reliability.Study designCohort study (diagnosis); Level of evidence, 3.MethodsEleven fellowship-trained orthopaedic surgeon investigators reviewed 75 video clips containing arthroscopic evaluation of a torn ACL and then completed the 6-question ACL Pathology Evaluation Form. Agreement statistics including exact agreement, Fleiss ?, Gwet agreement coefficient 1 (AC1), and Gwet AC2 were then calculated to assess interobserver reliability.ResultsIn aggregate, the multiple assessments of observer reproducibility revealed that surgeon participants in this study, when evaluating the same injury, agreed roughly 80% of the time on whether (1) at least 50% of the tibial footprint remained, (2) the remaining tibial stump was ?10 mm, and (3) the injury was therefore reparable using the BEAR procedure. Participants also agreed roughly 60% of the time on exactly how many suturable bundles were available. These characteristics are believed to be most important, among those studied, in determining whether a torn ACL is amenable to midsubstance repair.ConclusionThis study is the first of its kind to demonstrate the interobserver reliability of arthroscopic classification of ACL tears. We have demonstrated that this classification system, though not ideally reproducible, is reliable enough across surgeons at multiple institutions for use in multicenter studies.RegistrationNCT03776162 (ClinicalTrials.gov identifier).

Project description:ObjectiveTo compare, in young active adults with an acute anterior cruciate ligament (ACL) tear, the mid-term (five year) patient reported and radiographic outcomes between those treated with rehabilitation plus early ACL reconstruction and those treated with rehabilitation and optional delayed ACL reconstruction.DesignExtended follow-up of prospective randomised controlled trial.SettingOrthopaedic departments at two hospitals in Sweden.Participants121 young, active adults (mean age 26 years) with acute ACL injury to a previously uninjured knee. One patient was lost to five year follow-up.InterventionAll patients received similar structured rehabilitation. In addition to rehabilitation, 62 patients were assigned to early ACL reconstruction and 59 were assigned to the option of having a delayed ACL reconstruction if needed.Main outcome measureThe main outcome was the change from baseline to five years in the mean value of four of the five subscales of the knee injury and osteoarthritis outcome score (KOOS(4)). Other outcomes included the absolute KOOS(4) score, all five KOOS subscale scores, SF-36, Tegner activity scale, meniscal surgery, and radiographic osteoarthritis at five years.ResultsThirty (51%) patients assigned to optional delayed ACL reconstruction had delayed ACL reconstruction (seven between two and five years). The mean change in KOOS(4) score from baseline to five years was 42.9 points for those assigned to rehabilitation plus early ACL reconstruction and 44.9 for those assigned to rehabilitation plus optional delayed reconstruction (between group difference 2.0 points, 95% confidence interval -8.5 to 4.5; P=0.54 after adjustment for baseline score). At five years, no significant between group differences were seen in KOOS(4) (P=0.45), any of the KOOS subscales (P ≥ 0.12), SF-36 (P ≥ 0.34), Tegner activity scale (P=0.74), or incident radiographic osteoarthritis of the index knee (P=0.17). No between group differences were seen in the number of knees having meniscus surgery (P=0.48) or in a time to event analysis of the proportion of meniscuses operated on (P=0.77). The results were similar when analysed by treatment actually received.ConclusionIn this first high quality randomised controlled trial with minimal loss to follow-up, a strategy of rehabilitation plus early ACL reconstruction did not provide better results at five years than a strategy of initial rehabilitation with the option of having a later ACL reconstruction. Results did not differ between knees surgically reconstructed early or late and those treated with rehabilitation alone. These results should encourage clinicians and young active adult patients to consider rehabilitation as a primary treatment option after an acute ACL tear.Trial registrationCurrent Controlled Trials ISRCTN84752559.

Project description:PurposeTo assess the influence of demographic risk factors, anatomic risk factors, and injury mechanisms on anterior cruciate ligament (ACL) tear patterns.MethodsAll patients undergoing knee magnetic resonance imaging at our institution for acute ACL tears (within 1 month of injury) in 2019 were retrospectively analyzed. Patients with partial ACL tears and full-thickness posterior cruciate ligament injuries were excluded. On sagittal magnetic resonance images, the proximal and distal remnant lengths were measured, and the tear location was calculated as the distal remnant length divided by the total remnant length. Previously reported demographic and anatomic risk factors associated with ACL injury were then reviewed, including the notch width index, notch angle, intercondylar notch stenosis, alpha angle, posterior tibial slope, meniscal slope, and lateral femoral condyle index. In addition, the presence and severity of bone bruises were recorded. Finally, risk factors associated with ACL tear location were further analyzed using multivariate logistic regression.ResultsA total of 254 patients (44% male patients; mean age, 34 years; age range, 9-74 years) were included, of whom 60 (24%) had a proximal ACL tear (tear at the proximal quarter). Multivariate enter logistic regression analysis showed that older age (P = .008) was predictive of a more proximal tear location whereas open physes (P = .025), bone bruises in both compartments (P = .005), and posterolateral corner injury (P = .017) decreased the likelihood of a proximal tear (R 2 = 0.121, P < .001).ConclusionsNo anatomic risk factors were identified to play a role in tear location. Although most patients have midsubstance tears, proximal ACL tears were more commonly found in older patients. Bone contusions involving the medial compartment are associated with midsubstance tears; these findings may indicate that different injury mechanisms play a role in the location at which the ACL tears.Level of evidenceLevel III, prognostic, retrospective cohort study.

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Anterior cruciate ligament tear induces a sustained loss of muscle fiber force production.

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Anterior cruciate ligament tear induces a sustained loss of muscle fiber force production.

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